Bulk acoustic wave resonator having a plurality of compensation layers and duplexer using same

ABSTRACT

A bulk acoustic wave resonator (BAWR) includes a bulk acoustic resonance unit and at least one compensation layer. The bulk acoustic resonance unit includes a first electrode, a second electrode, and a piezoelectric layer disposed between the first electrode and the second electrode. The first electrode, the second electrode, and the piezoelectric layer each include a material that modifies a resonance frequency based on a temperature, and the at least one compensation layer includes a material that adjusts the resonance frequency modified based on the temperature in a direction opposite to a direction of the modification.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/558,907 filed on Jul. 26, 2012, which claims the benefit of KoreanPatent Application No. 10-2011-0074616 filed on Jul. 27, 2011, in theKorean Intellectual Property Office, the entire disclosure of which isincorporated herein by reference for all purposes.

BACKGROUND 1. Field

The following description relates to a bulk acoustic wave resonator(BAWR).

2. Description of Related Art

A mobile communication terminal transmits and receives a communicationsignal. The signal transmission is performed using a transmissionfrequency, and the signal reception is performed using a receptionfrequency. To prevent interference between a transmitted signal and areceived signal, a predetermined band gap is required between thetransmission frequency and the reception frequency. However, frequencyresources are limited, and the band gap reduces the available frequencyresources because it cannot be used for communication. Therefore theband gap needs to be reduced to increase the frequency resources thatare available for communication.

SUMMARY

According to an aspect, a bulk acoustic wave resonator (BAWR) includes abulk acoustic resonance unit including a first electrode; a secondelectrode; and a piezoelectric layer disposed between the firstelectrode and the second electrode; each of the first electrode, thesecond electrode, and the piezoelectric layer including a material thatmodifies a resonance frequency based on a temperature; the BAWR furtherincluding at least one compensation layer including a material thatadjusts the resonance frequency modified based on the temperature in adirection opposite to a direction of the modification.

The at least one compensation layer may adjust a temperature coefficientof the bulk acoustic wave resonance unit, and may include a compensationlayer disposed between the first electrode or the piezoelectric layer,or between the piezoelectric layer and the second electrode, or mayinclude a first compensation layer and a second compensation layerdisposed so that the first compensation layer is between the firstelectrode and the piezoelectric layer, and the second compensation layeris between the piezoelectric layer and the second electrode.

The at least one compensation layer may adjust a temperature coefficientof the bulk acoustic wave resonance unit, and may include a compensationlayer disposed so that the first electrode is between the compensationlayer and the piezoelectric layer, or so that the compensation layer isbetween the first electrode and the piezoelectric layer, or may includea first compensation layer and a second compensation layer disposed sothat the first electrode is between the first compensation layer and thesecond compensation layer, and the second compensation layer is betweenthe first electrode and the piezoelectric layer.

The at least one compensation layer may adjust a temperature coefficientof the bulk acoustic wave resonance unit, and may include a compensationlayer disposed so that the compensation layer is between thepiezoelectric layer and the second electrode, or so that the secondelectrode is between the piezoelectric layer and the compensation layer,or may include a first compensation layer and a second compensationlayer disposed so that the first compensation layer is between thepiezoelectric layer and the second electrode, and the second electrodeis between the first compensation layer and the second compensationlayer.

The at least one compensation layer may include a first compensationlayer disposed so that the first electrode is between the firstcompensation layer and the piezoelectric layer; and a secondcompensation layer disposed so that the second electrode is between thepiezoelectric layer and the second compensation layer.

A sum of a thickness of each compensation layer of the at least onecompensation layer may be less than or equal to a sum of a thickness ofthe first electrode, a thickness of the piezoelectric layer, and athickness of the second electrode.

A sum of a thickness of each compensation layer of the at least onecompensation layer may be less than or equal to 2 micrometers (μm).

The at least one compensation layer may include a silicon oxide-basedmaterial or a silicon nitride-based material.

The at least one compensation layer may include silicon oxide doped withany impurity, or silicon nitride doped with an impurity.

The impurity may include at least one element selected from the groupconsisting of arsenic (As), antimony (Sb), phosphorus (P), boron (B),germanium (Ge), silicon (Si), and aluminum (Al).

The BAWR may further include a membrane contacting the bulk acousticresonance unit; wherein the at least one compensation layer may includea compensation layer that is a portion of the membrane that has beendoped with an impurity.

The at least one compensation layer may include a compensation layerdisposed so that the first electrode is between the compensation layerand the piezoelectric layer; and the BAWR may further include a propertycompensation layer disposed on the compensation layer so that thecompensation layer is between the property compensation layer and thefirst electrode; and the property compensation layer may be disposed onedges of a surface of the compensation layer so that a remaining portionof the surface between the edges is not covered by the propertycompensation layer.

The at least one compensation layer may include a first compensationlayer contacting the first electrode so that the first electrode isbetween the first compensation layer and the piezoelectric layer; and asecond compensation layer contacting the first compensation layer sothat the first compensation layer is between the second compensationlayer and the first electrode.

The at least one compensation layer may include a first compensationlayer contacting the first electrode so that the first electrode isbetween the first compensation layer and the piezoelectric layer; asecond compensation layer contacting the second electrode so that thesecond electrode is between the piezoelectric layer and the secondcompensation layer; and a third compensation layer contacting the secondcompensation layer so that the second compensation layer is between thesecond electrode and the third compensation layer.

According to an aspect, a bulk acoustic wave resonator (BAWR) includes asubstrate; an air cavity disposed on a portion of the substrate; a bulkacoustic wave resonance unit including a first electrode disposed sothat the air cavity is between a portion of the first electrode and theportion of the substrate; a second electrode disposed so that a portionof the second electrode is between the portion of the first electrodeand the air cavity; and a piezoelectric layer disposed so that a portionof the piezoelectric layer is between the portion of the first electrodeand the portion of the second electrode; the BAWR further including acompensation layer disposed so that a portion of the compensation layeris between the portion of the second electrode and the air cavity, or sothat the portion of the first electrode is between a portion of thecompensation layer and the portion of the piezoelectric layer; whereinthe compensation layer includes a material that adjusts a resonancefrequency that is modified in the bulk acoustic wave resonance unitbased on a temperature in a direction opposite to a direction of themodification.

The compensation layer may be a first compensation layer disposed sothat a portion of the first compensation layer is between the portion ofthe second electrode and the air cavity; the BAWR may further include asecond compensation layer disposed so that the portion of the firstelectrode is between a portion of the second compensation layer and theportion of the piezoelectric layer; and the second compensation layermay include a material that adjusts the modified resonance frequency inthe direction opposite to the direction of the modification.

The BAWR may further include a third compensation layer disposed so thata portion of the third compensation layer is between the portion of thefirst compensation layer and the air cavity; wherein the thirdcompensation layer may include a material that adjusts the modifiedresonance frequency in the direction opposite to the direction of themodification.

The BAWR may further include a fourth compensation layer disposed sothat the portion of the second compensation layer is between a portionof the fourth compensation layer and the portion of the first electrode;wherein the fourth compensation layer may include a material thatadjusts the modified resonance frequency in the direction opposite tothe direction of the modification.

The BAWR may further include a third compensation layer disposed so thatthe portion of the second compensation layer is between a portion of thethird compensation layer and the portion of the first electrode; whereinthe third compensation layer may include a material that adjusts themodified resonance frequency in the direction opposite to the directionof the modification.

A sum of a thickness of the first compensation layer and a thickness ofthe second compensation layer may be less than or equal to a sum of athickness of the first electrode, a thickness of the piezoelectriclayer, and a thickness of the second electrode.

According to an aspect, a duplexer includes a first filter configured tofilter a transmission signal received from a transmit input of theduplexer, and output the filtered transmission signal to an antenna; aphase shifter configured to shift a phase of a received signal receivedfrom the antenna, and output the phase-shifted received signal; and asecond filter configured to filter the phase-shifted received signaloutput from the phase shifter, and output the filtered phase-shiftedreceived signal to a receive output of the duplexer; wherein the firstfilter and the second filter operate at different predeterminedresonance frequencies; the phase shifter is further configured to shiftthe phase of the received signal to prevent signal interference betweenthe first filter and the second filter; and each of the first filter andthe second filter includes a bulk acoustic source resonance unitincluding a first electrode; a second electrode; and a piezoelectriclayer; each of the first electrode, the second electrode, and thepiezoelectric layer including a material that modifies a resonancefrequency based on a temperature; each of the first filter and thesecond filter further including at least one compensation layerincluding a material that adjusts the modified resonance frequency in adirection opposite to a direction of the modification.

According to an aspect, a bulk acoustic wave resonator (BAWR) includes abulk acoustic wave resonance unit including a first electrode; a secondelectrode; and a piezoelectric layer disposed between the firstelectrode and the second electrode; each of the first electrode, thesecond electrode, and the piezoelectric layer including a material thatmodifies a resonance frequency based on a temperature; the BAWR furtherincluding at least one compensation layer to adjust the resonancefrequency modified based on the temperature in a direction opposite to adirection of the modification; wherein a sum of a temperaturecoefficient of frequency (TCF) of the bulk acoustic wave resonance unitand a TCF of the at least one compensation layer is substantially zero.

The BAWR may further include a substrate; and an air cavity disposed ona portion of the substrate; wherein the second electrode may be disposedso that the air cavity is between a portion of the second electrode andthe portion of the substrate; the piezoelectric layer may be disposed sothat the portion of the second electrode is between a portion of thepiezoelectric layer and the air cavity; the first electrode may bedisposed so that the portion of the piezoelectric layer is between aportion of the first electrode and the portion of the second electrode;and the at least one compensation layer may include a compensation layerdisposed so that a portion of the compensation layer is between theportion of the second electrode and the air cavity, or so that theportion of the first electrode is between a portion of the compensationlayer and the portion of the piezoelectric layer.

A sum of a thickness of each compensation layer of the at least onecompensation layer may be less than or equal to a sum of a thickness ofthe first electrode, a thickness of the piezoelectric layer, and athickness of the second electrode.

According to an aspect, a bulk acoustic wave resonator (BAWR) includes asubstrate including a surface, the surface including a first portion, asecond portion, and a third portion, the second portion being betweenthe first portion and the third portion; an air cavity disposed on thesecond portion of the surface of the substrate; a bulk acoustic waveresonance unit including a first electrode disposed so that a firstportion of the first electrode opposes the first portion of the surfaceof the substrate, and the air cavity is between a second portion of thefirst electrode and the second portion of the surface of the substrate;a second electrode disposed so that a first portion of the secondelectrode opposes the third portion of the surface of the substrate, anda second portion of the second electrode is between the second portionof the first electrode and the air cavity; and a piezoelectric layerdisposed so that a first portion of the piezoelectric layer is betweenthe first portion of the first electrode and the first portion of thesurface of the substrate, a second portion of the piezoelectric layer isbetween the second portion of the first electrode and the second portionof the second electrode, and the first portion of the second electrodeis between a third portion of the piezoelectric layer and the thirdportion of the surface of the substrate; the BAWR further including atleast one compensation layer including a material that adjusts aresonance frequency that is modified in the bulk acoustic wave resonanceunit based on a temperature in a direction opposite to a direction ofthe modification.

According to an aspect, the at least one compensation layer may includeany one or more of the following compensation layers: a compensationlayer disposed so that a first portion of the compensation layer isbetween the first portion of the piezoelectric layer and the firstportion of the surface of the substrate, a second portion of thecompensation layer is between the second portion of the second electrodeand the air cavity, and a third portion of the compensation layer isbetween the first portion of the second electrode and the third portionof the surface of the substrate; a compensation layer disposed so that afirst portion of the compensation layer is between the first portion ofthe piezoelectric layer and the first portion of the surface of thesubstrate, a second portion of the compensation layer is disposedbetween the second portion of the second electrode and the secondportion of the piezoelectric layer, and a third portion of thecompensation layer is disposed between the third portion of thepiezoelectric layer and the first portion of the second electrode; acompensation layer disposed so that a first portion of the compensationlayer is between the first portion of the first electrode and the firstportion of the piezoelectric layer, a second portion of the compensationlayer is between the second portion of the first electrode and thesecond portion of the piezoelectric layer, and the third portion of thepiezoelectric layer is between a third portion of the compensation layerand the first portion of the second electrode; and a compensation layerdisposed so that the first portion of the first electrode is between afirst portion of the compensation layer and the first portion of thepiezoelectric layer, the second portion of the first electrode isbetween a second portion of the compensation layer and the secondportion of the piezoelectric layer, and the third portion of thepiezoelectric layer is between a third portion of the compensation layerand the first portion of the second electrode.

According to an aspect, the at least one compensation layer may includeeither one or both of the following pairs of compensation layers: a pairof compensation layers contacting one another and disposed so that afirst portion of the pair of compensation layers is between the firstportion of the piezoelectric layer and the first portion of the surfaceof the substrate, a second portion of the pair of compensation layers isbetween the second portion of the second electrode and the air cavity,and a third portion of the pair of compensation layers is between thefirst portion of the second electrode and the third portion of thesurface of the substrate; and a pair of compensation layers contactingone another and disposed so that the first portion of the firstelectrode is between a first portion of the pair of compensation layersand the first portion of the piezoelectric layer, the second portion ofthe first electrode is between a second portion of the pair ofcompensation layers and the second portion of the piezoelectric layer,and the third portion of the piezoelectric layer is between a thirdportion of the pair of compensation layers and the first portion of thesecond electrode.

According to an aspect, a temperature coefficient of the BAWR may beadjusted by adding, on or below a piezoelectric layer, or on and below apiezoelectric layer, a compensation layer that adjusts a temperaturecoefficient of frequency (TCF). Therefore, a BAWR having a low TCF maybe provided.

According to a aspect, a BAWR having a low TCF may be used in a filterand a duplexer to provide an appropriately narrow band gap between atransmission frequency and a reception frequency.

According to an aspect, a BAWR having a low TCF may be used in a filterto decrease a change in a frequency characteristic of the filter basedon a change in a temperature.

According to an aspect, a BAWR having a low TCF may be used in a mobilecommunication terminal to provide reliable operation within a range ofan ambient temperature at which the mobile communication terminal isused.

According to an aspect, a temperature coefficient of a BAWR may beadjusted by doping, with an impurity element, a portion of a membrane ora portion of a passivation layer of an upper portion electrode of theBAWR, and thus may provide degrees of freedom in product design withoutmodification of a structure of the BAWR.

According to an aspect, a compensation layer may be provided in an BAWRto adjust a temperature coefficient of frequency (TCF) of the BAWR, anda portion of the compensation layer may be etched or an additional layermay be provided on a portion of the compensation adjust a quality factor(Q) value of the BAWR.

Other features and aspects will be apparent from the following detaileddescription, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a band gap between a transmission frequency and areception frequency of a mobile communication terminal.

FIG. 2 illustrates an example of a bulk acoustic wave resonator (BAWR).

FIG. 3 illustrates another example of a BAWR.

FIG. 4 illustrates another example of a BAWR.

FIG. 5 illustrates another example of a BAWR.

FIG. 6 illustrates another example of a BAWR.

FIG. 7 illustrates another example of a BAWR.

FIG. 8 illustrates an example of a BAWR in which a Q factor of the BAWRis adjusted.

FIG. 9 is a sectional view illustrating an example of a layeredstructure of a BAWR.

FIGS. 10 through 18 are sectional views illustrating other examples of alayered structure of a BAWR.

FIG. 19 is a block diagram of an example of a duplexer.

DETAILED DESCRIPTION

The following detailed description is provided to assist the reader ingaining a comprehensive understanding of the methods, apparatuses and/orsystems described herein. Accordingly, various changes, modifications,and equivalents of the methods, apparatuses and/or systems describedherein will be apparent to one of ordinary skill in the art. Anysequences of processing steps and/or operations described herein aremerely examples, and the sequences of processing steps and/or operationsis not limited to the specific examples set forth herein, and may bechanged as will be apparent to one of ordinary skill in the art, withthe exception of processing steps and/or operations necessarilyoccurring in a certain order. Also, descriptions of well-known functionsand constructions may be omitted for increased clarity and conciseness.

Throughout the drawings and the detailed description, the same referencenumerals refer to the same elements, features, and structures. Therelative size and depiction of these elements may be exaggerated forclarity, illustration, and convenience.

In the following description and the claims, when a first element isdescribed as being between a second element and the third element, oneor more other elements may also be present between the first element andthe second element, and/or between the first element and the thirdelements.

A bulk acoustic wave resonator (BAWR) operates through electrodesdisposed on or below a piezoelectric layer, or on and below thepiezoelectric layer. In response to a high frequency electric potentialapplied to the electrodes, the piezoelectric layer oscillates. Thus, theBAWR may operate as a filter. The BAWR may be elevated above a substrateto provide an air cavity to improve a reflection characteristic of anacoustic wave.

In a case of a BAWR having a frequency band-pass characteristic, aplurality of resonators may be disposed on a plane and connected to acommon electrode to improve a reflection characteristic or atransmission characteristic within a frequency band range.

The BAWR may be used in a filter, a transmitter, a receiver, or aduplexer in a wireless communication device for input and output ofwireless data. There are various types of wireless communication devicesfor various purposes, and a number of wireless devices conventionallyregarded as wired devices has rapidly increased. Thus, a number offields to which the BAWR may be applied has expanded.

The BAWR may be a device that induces an oscillation or waves of apredetermined frequency using resonance, and the device may be used as acomponent in a resonance frequency (RF) device, for example, a filterand an oscillator.

FIG. 1 illustrates a band gap between a transmission frequency and areception frequency of a mobile communication terminal.

Frequency resources that mobile communication devices may use arelimited. Therefore, each mobile communication device performscommunication based on an allocated frequency band. To preventinterference from occurring between a transmitted signal and a receivedsignal, a band gap is needed between a transmission frequency band forsignal transmission and a reception frequency band for signal reception.Reducing a band gap between allocated frequency bands can provide awider frequency band to increase an amount of data that can betransmitted and received. Thus, there is a need for an apparatus that iscapable of performing communication using a narrow frequency band gapwithout interference occurring between a transmitted signal and areceived signal.

Referring to FIG. 1, a transmission frequency band increases by a width101 and a reception frequency band increases by a width 103 to meet thedemands of communication companies. As the transmission frequency bandincreases by the width 101, a band gap 110 decreases to a band gap 120.

A duplexer may be implemented using a bulk acoustic wave resonator(BAWR) that separates a transmitted signal and a received signal. Inthis example, to accurately and effectively separate the transmittedsignal and the received signal within the narrowed band gap 120, a BAWRhaving a high quality factor (Q) value and a low temperature coefficientof frequency (TCF) are required. The TCF of the BAWR is a ratio of afrequency variation of the BAWR within a range of a temperature at whichthe BAWR is used. The closer TCF is to zero, the lower a frequencyvariance based on a temperature will be.

According to an example, a BAWR having a low TCF is used for a duplexerthat separates a transmitted signal and a received signal within anarrow band gap.

FIG. 2 illustrates an example of a BAWR.

Referring to FIG. 2, the BAWR includes a bulk acoustic wave resonanceunit 210 and at least one compensation layer 220. The bulk acoustic waveresonance unit 210 includes an upper portion electrode 211, apiezoelectric layer 213, and a lower portion electrode 215. The lowerportion electrode 215 is disposed on a membrane 225, the piezoelectriclayer 213 is disposed on the lower portion electrode 215, and the upperportion electrode 211 is disposed on the piezoelectric layer 213.

The piezoelectric layer 213 includes a material that modifies aresonance frequency based on a change in an ambient temperature, and mayhave a TCF in a range from about −200 parts per million (ppm)/° C. toabout 200 ppm/° C. Examples of the material included in thepiezoelectric layer 213 include zinc oxide (ZnO), aluminum nitride(AlN), and the like. In this example, a TCF of ZnO is about −99 ppm/° C.and a TCF of AlN is about −26 ppm/° C.

The upper portion electrode 211 includes a material that modifies aresonance frequency based on a change in an ambient temperature.Examples of the material included in the upper portion electrode 211include molybdenum (Mo), ruthenium (Ru), tungsten (W), platinum (Pt),aluminum (Al), gold (Au), and the like. In this example, a TCF of thematerial included in the upper portion electrode 211 may be in a rangefrom about −200 ppm/° C. to about 200 ppm/° C.

The lower portion electrode 215 includes a material that modifies aresonance frequency based on a change in an ambient temperature.Examples of the material include Mo, Ru, W, Pt, Al, Au, and the like. Inthis example, a TCF of the material included in the lower portionelectrode 215 may be in a range from about −200 ppm/° C. to about 200ppm/° C.

The material included in the upper portion electrode 211 and thematerial included in the lower portion electrode 215 may be the same, ormay be different from each other. A TCF of the bulk acoustic waveresonance unit 210 is determined based on the TCF of the upper portionelectrode 211, the TCF of the piezoelectric layer 213, and the TCF ofthe lower portion electrode 215. The TCF of the bulk acoustic waveresonator 210 may be in a range from about −200 ppm/° C. to about 200ppm/° C.

At least one compensation layer 220 includes a compensation layer 221and a compensation layer 223. The compensation layer 221 is disposed onthe upper portion electrode 211, and the compensation layer 223 isdisposed below the lower portion electrode 215. The membrane 225supporting the bulk acoustic wave resonance unit 210 is disposed betweenthe lower portion electrode 215 and the compensation layer 223. Thecompensation layer 223 may be formed by doping a portion of the membrane225 with an impurity element.

The compensation layer 221 and the compensation layer 223 include amaterial that modifies a resonance frequency based on a change in anambient temperature. In particular, the compensation layer 221 and thecompensation layer 223 include a material that adjusts a resonancefrequency that is modified in the bulk acoustic wave resonance unit 210based on a change in an ambient temperature in a direction opposite to adirection of the modification. The material included in the compensationlayer 221 and the compensation layer 223 may include a siliconoxide-based material or a silicon nitride-based material. In thisexample, a TCF of the material included in the compensation layer 221and the compensation layer 223 may be in a range from about 200 ppm/° C.to about 200 ppm/° C.

The compensation layer 221 and the compensation layer 223 may be formedby doping silicon oxide (SiO₂) or silicon nitride (Si₃N₄) with animpurity element. The TCF of the compensation layer 221 and thecompensation layer 223 may be more finely adjusted by the doping with animpurity element. An example of the impurity element may include atleast one element selected from the group consisting of arsenic (As),antimony (Sb), phosphorus (P), boron (B), germanium (Ge), silicon (Si),and aluminum (Al). For example, the impurity element may include oneelement selected from the group consisting of As, Sb, P, B, Ge, Si, andAl, or two elements selected from the group consisting of As, Sb, P, B,Ge, Si, and Al.

The impurity element may be deposited using an impurity gas includingthe impurity element based on an in-situ deposition simultaneously withdeposition of SiO₂ or Si₃N₄. Alternatively, SiO₂ or Si₃N₄ may be dopedwith the impurity element by ion implantation after the SiO₂ or Si₃N₄are deposited.

A sum of a thickness of the compensation layer 221 and a thickness ofthe compensation layer 223 may be less than or equal to a sum of athickness of the upper portion electrode 211, a thickness of thepiezoelectric layer 213, and a thickness of the lower portion electrode215. The thickness of the compensation layer 221 and the thickness ofthe compensation layer 223 may be determined based on a Q factor of thebulk acoustic wave resonance unit 210. For example, the compensationlayer 221 and the compensation layer 223 may be layered to be as thin aspossible within a range allowed by available techniques. As a thicknessof a compensation layer increases, the Q factor of the bulk acousticwave resonance unit 210 decreases. A sum of the thickness of thecompensation layer 221 and the thickness of the compensation layer 223may be less than or equal to a value of 2 μm.

The compensation layer 221 and the compensation layer 223 adjust the TCFof the bulk acoustic wave resonance unit 210. For example, when the TCFof the bulk acoustic wave resonance unit 210 is less than or equal to−200 ppm/° C., the TCF of the compensation layer 221 and thecompensation layer 223 may be about +200 ppm/° C., based on a materialincluded in the compensation layer 221 and the compensation layer 223.Accordingly, a TCF of the BAWR may be adjusted to be close to zero,i.e., to be substantially zero, by using the compensation layer 221 andthe compensation layer 223. Accordingly, the BAWR may have a low TCF.

The BAWR has a higher Q factor when thin compensation layers aredisposed on an upper portion electrode and below a lower portionelectrode, than when a single thick compensation layer is disposed onthe upper portion electrode or disposed below the lower portionelectrode.

FIG. 3 illustrates another example of a BAWR.

Referring to FIG. 3, the BAWR includes a bulk acoustic wave resonanceunit and compensation layers. The bulk acoustic wave resonance unitincludes an upper portion electrode 310, a piezoelectric layer 330, anda lower portion electrode 340. The lower portion electrode 340 isdisposed on a compensation layer 350, the piezoelectric layer 330 isdisposed on the lower portion electrode 340, and the upper portionelectrode 310 is disposed on a compensation layer 320.

When compared to the BAWR of FIG. 2, the BAWR of FIG. 3 is different inthat the compensation layer 320 is disposed on the piezoelectric layer330 and below the upper portion electrode 310. Other descriptionsassociated with the upper portion electrode 310, the piezoelectric layer330, the lower portion electrode 340, the compensation layer 320, andthe compensation layer 350 are the same as the descriptions associatedwith the upper portion electrode 211, the piezoelectric layer 213, thelower portion electrode 215, and the compensation layers 221 and 223 ofFIG. 2, and repeated descriptions will be omitted for conciseness.

FIG. 4 illustrates another example of a BAWR.

Referring to FIG. 4, the bulk acoustic wave resonance unit includes anupper portion electrode 420, a piezoelectric layer 440, and a lowerportion electrode 450. The lower portion electrode 450 is disposed on acompensation layer 460, the piezoelectric layer 440 is disposed on thelower portion electrode 450, a compensation layer 430 is disposed on thepiezoelectric layer 440, and the upper portion electrode 420 is disposedon the compensation layer 430 and below a compensation layer 410.

A sum of a thickness of the compensation layer 410, a thickness of thecompensation layer 430, and a thickness of the compensation layer 460may be less than or equal to a sum of a thickness of the upper portionelectrode 420, a thickness of piezoelectric layer 440, and a thicknessof the lower portion electrode 450.

When compared to the BAWR of FIG. 2, the BAWR of FIG. 4 is different inthat the compensation layer 430 is additionally included on thepiezoelectric layer 440 and below the upper portion electrode 420. Otherdescriptions associated with the upper portion electrode 420, thepiezoelectric layer 440, the lower portion electrode 450, thecompensation layer 410, and the compensation layer 460 are the same asthe descriptions associated with the upper portion electrode 211, thepiezoelectric layer 213, the lower portion electrode 215, and thecompensation layers 221 and 223 of FIG. 2, and repeated descriptionswill be omitted for conciseness.

FIG. 5 illustrates another example of a BAWR.

Referring to FIG. 5, the bulk acoustic wave resonance unit includes anupper portion electrode 510, a piezoelectric layer 520, and a lowerportion electrode 530. The lower portion electrode 530 is disposed on acompensation layer 540, the piezoelectric layer 520 is disposed on thelower portion electrode 530, and the upper portion electrode 510 isdisposed on the piezoelectric layer 520.

A thickness of the compensation layer 540 may be less than or equal to asum of a thickness of the upper portion electrode 510, a thickness ofthe piezoelectric layer 520, a thickness of the lower portion electrode530, or the thickness of the compensation layer 540 may be less than orequal to the thickness of the piezoelectric layer 520.

When compared to the BAWR of FIG. 2, the BAWR of FIG. 5 is different inthat the single compensation layer 540 is used. A Q factor will be lowerwhen a single compensation layer is used than when a plurality ofcompensation layers is used. Other descriptions associated with theupper portion electrode 510, the piezoelectric layer 520, the lowerportion electrode 530, and the compensation layer 540 are the same asthe descriptions associated with the upper portion electrode 211, thepiezoelectric layer 213, the lower portion electrode 215, and thecompensation layers 221 and 223 of FIG. 2, and repeated descriptionswill be omitted for conciseness.

FIG. 6 illustrates another example of a BAWR.

Referring to FIG. 6, a bulk acoustic wave resonance unit includes anupper portion electrode 620, a piezoelectric layer 630, and a lowerportion electrode 640. The piezoelectric layer 630 is disposed on thelower portion electrode 640, and the upper portion electrode 620 isdisposed on the piezoelectric layer 630. A compensation layer 610 isdisposed on the upper portion electrode 620. A thickness of thecompensation layer 610 may be less than or equal to a sum of a thicknessof the upper portion electrode 620, a thickness of the piezoelectriclayer 630, and a thickness of the lower portion electrode 640, or thethickness of the compensation layer 610 may be less than or equal to thethickness of the piezoelectric layer 630.

When compared to the BAWR of FIG. 5, the BAWR of FIG. 6 is different inthat the compensation layer 610 is disposed on the upper portionelectrode 620. Other descriptions associated with the upper portionelectrode 620, the piezoelectric layer 630, the lower portion electrode640, and the compensation layer 610 are the same as the descriptionsassociated with the upper portion electrode 211, the piezoelectric layer213, the lower portion electrode 215, and the compensation layers 221and 223 of FIG. 2, and repeated descriptions will be omitted forconciseness.

FIG. 7 illustrates another example of a BAWR.

Referring to FIG. 7, the bulk acoustic wave resonance unit includes anupper portion electrode 720, a piezoelectric layer 740, and a lowerportion electrode 760. The lower portion electrode 760 is disposed on acompensation layer 770 and below a compensation layer 750. Thepiezoelectric layer 740 is disposed on the compensation layer 750 andbelow a compensation layer 730. The upper portion electrode 720 isdisposed on the compensation layer 730 and below a compensation layer710.

A passivation layer (not illustrated) may be disposed on the upperportion electrode 720. The compensation layer 710 may be formed bydoping a portion of the passivation layer with an impurity element. Asum of a thickness of the compensation layer 710, a thickness of thecompensation layer 730, a thickness of the compensation layer 750, and athickness of the compensation layer 770 may be less than or equal to asum of a thickness of the upper portion electrode 720, a thickness ofthe piezoelectric layer 740, and a thickness of the lower portionelectrode 760, or may be less than or equal to the thickness of thepiezoelectric layer 740.

When compared to the BAWR of FIG. 2, the BAWR of FIG. 7 is different inthat the compensation layer 730 is additionally disposed on thepiezoelectric layer 740 and below the upper portion electrode 720, andthe compensation layer 750 is additionally disposed on the lower portionelectrode 760 and below the piezoelectric layer 740. Other descriptionsassociated with the upper portion electrode 720, the piezoelectric layer740, the lower portion electrode 760, the compensation layers 710 and770 are the same as the descriptions associated with the upper portionelectrode 211, the piezoelectric layer 213, the lower portion electrode215, and the compensation layers 221 and 223 of FIG. 2, and repeateddescriptions will be omitted for conciseness.

FIG. 8 illustrates an example of a BAWR in which a Q factor of the BAWRis adjusted.

Referring to FIG. 8, the BAWR includes a bulk acoustic wave resonanceunit and compensation layers 810 and 850. The bulk acoustic waveresonance unit includes an upper portion electrode 820, a piezoelectriclayer 830, and a lower portion electrode 840. The lower portionelectrode 840 is disposed on a compensation layer 850, the piezoelectriclayer 830 is disposed on the lower portion electrode 840, and the upperportion electrode 820 is disposed on the piezoelectric layer 830. Thecompensation layer 810 is disposed on the upper portion electrode 820,and the compensation layer 850 is disposed below the lower portionelectrode 840.

To improve a Q factor of the BAWR, property compensation layers 891 and893 are disposed on portions of the compensation layer 810. Inparticular, when the property compensation layers 891 and 893 areprovided, the Q factor of the BAWR increases. A thickness of theproperty compensation layers 891 and 893 may be selected to provide adesired Q factor. Examples of a material included in the propertycompensation layers 891 and 893 may be varied. For example, the materialincluded in the property compensation layers 891 and 893 may be amaterial included in the compensation layer 810, which may be, forexample, silicon oxide (SiO₂) or silicon nitride (Si₃N₄) doped with animpurity element. An example of the impurity element may include atleast one element selected from the group consisting of arsenic (As),antimony (Sb), phosphorus (P), boron (B), germanium (Ge), silicon (Si),and aluminum (Al) For example, the impurity element may include oneelement selected from the group consisting of As, Sb, P, B, Ge, Si, andAl, or two elements selected from the group consisting of As, Sb, P, B,Ge, Si, and Al. The property compensation layer 891 and the propertycompensation layer 893 may have structures connected to each other. Theproperty compensation layers 891 and 893 may be disposed on edges of anupper portion of the compensation layer 810 as shown in FIG. 8 so thatan interior of the upper portion of the compensation layer 810 may beempty.

In the BAWR in FIG. 8, thicknesses of portions 860 and 880 in which theproperty compensation layers 891 and 893 are provided are different froma thickness of a portion 870 in which a property compensation layer isnot provided. Accordingly, the difference in thickness causes adifference in impedance between the portions 860 and 880 and the portion870.

In response to a high frequency potential being provided to the upperportion electrode 820 and the lower portion electrode 840, thepiezoelectric layer 830 will oscillate. In this example, an acousticwave is generated in a vertical direction from the upper portionelectrode 820 to the lower portion electrode 840 and an acoustic wave isgenerated in a horizontal direction. When there is a difference inthickness between the portions 860 and 880 and the portion 870 in theBAWR, a difference in impedance will occur, and therefore the acousticwave in the horizontal direction will be reflected from the portions 860and 880. Therefore, the BAWR will not lose the acoustic wave in thehorizontal direction, and therefore the reflection characteristic willbe improved. Also, the Q factor of the BAWR may be improved as thereflection characteristic is improved.

In addition to the example shown in FIG. 8, when there is a differencein thickness between layered portions in a BAWR, a difference inimpedance will occur, and therefore the reflection characteristic may beimproved. Therefore, various schemes to create a difference in thicknessbetween different portions in the BAWR may be employed.

FIG. 9 is a sectional view illustrating a layered structure of a BAWR.

Referring to FIG. 9, the BAWR includes a substrate 910, an air cavity920, a bulk acoustic wave resonance unit, compensation layer 930, and acompensation layer 970.

The air cavity 920 is disposed on a portion of the substrate 910. Theair cavity 920 creates a change in an impedance of the BAWR to improvean acoustic wave reflection characteristic. The air cavity may be filledwith air, or may be filled with a dielectric substance. Example of asuitable dielectric substance include an inert gas, SiO₂, Si₃N₄,polysilicon, a polymer, and the like.

The bulk acoustic wave resonance unit includes a first electrode 960, asecond electrode 940, and a piezoelectric layer 950. The first electrode960 corresponds to an upper portion electrode and the second electrode940 corresponds to a lower portion electrode. In this example, based onthe piezoelectric layer 950, the electrodes are classified as the upperportion electrode and the lower portion electrode. The second electrode940 is disposed on the compensation layer 930. In this example, amembrane that supports the bulk acoustic wave resonance unit may beprovided between the second electrode 940 and the air cavity 920, andbetween the second electrode 940 and the substrate 910 where there is noair cavity 920. The compensation layer 930 may be formed by doping aportion of the membrane with an impurity element. The piezoelectriclayer 950 is disposed on the second electrode 940. The first electrode960 is disposed on the piezoelectric layer 950. The first electrode 960,the piezoelectric layer 950, and the second electrode 940 include amaterial that modifies a resonance frequency based on a change in anambient temperature. Examples of the material included in thepiezoelectric layer 950 are ZnO, AlN, quartz, and the like. Examples ofthe material included in the first electrode 960 and the secondelectrode 940 are Mo, Ru, W, Pt, Al, Au, and the like.

The material included in the first electrode 960 and the materialincluded in the second electrode 940 may be the same, or may bedifferent from each other. Accordingly, a TCF of the bulk acoustic waveresonance unit is determined based on a TCF of the first electrode 960,a TCF of the piezoelectric layer 950, and the TCF of the secondelectrode 940. The TCF of the bulk acoustic wave resonance unit may bein a range from about −200 ppm/° C. to about 200 ppm/° C.

The compensation layer 930 is disposed on the substrate 910 and the aircavity 920. The compensation layer 970 is disposed on the firstelectrode 960. The compensation layer 930 and the compensation layer 970include a material that modifies a resonance frequency that is modifiedin the bulk acoustic wave resonance unit based on a change in an ambienttemperature in a direction opposite to a direction of the modification.Examples of the material include a silicon oxide-based material or asilicon nitride-based material. In this example, a TCF of the materialmay be in a range from about −200 ppm/° C. to about 200 ppm/° C.

The compensation layer 930 and the compensation layer 970 adjust the TCFof the bulk acoustic wave resonance unit so that a TCF of the BAWR has avalue close to zero.

A BAWR manufacturing method according to an example sequentially layersa silicon oxide film, a silicon nitride film, and a sacrificial layer onthe substrate 910. Examples of a sacrificial material included in thesacrificial layer are polysilicon and a polymer. The silicon oxide filmand the silicon nitride film may be used to protect the substrate 910from etching. The silicon oxide film and the silicon nitride film may bereplaced with another material that protects the substrate 910 frometching, or may be omitted when one of ordinary skill in the artdetermines that a suitable result can be obtained with the particularmanufacturing process and technique being employed without using thesilicon oxide film and the silicon nitride film or the other material.

The sacrificial layer is patterned on the substrate 910 to have a shapeof the air cavity 920 to be formed below the bulk acoustic waveresonance unit. The shape of the air cavity 920 may be selected toprovide an appropriate Q factor for the BAWR. The compensation layer 930and a first conductive layer are sequentially layered on the patternedsacrificial layer. The compensation layer 930 may be layered to have athickness less than or equal to a sum of a thickness of the secondelectrode 940, a thickness of the piezoelectric layer 950, and athickness of the first electrode 960, or may be layered to have athickness less than or equal to the thickness of the piezoelectric layer950. The second electrode 940 is patterned on the first conductivelayer. The second electrode 940 shown in FIG. 9 is formed on only aportion of the compensation layer 930, but may have otherconfigurations. The piezoelectric layer 950 and a second conductivelayer are sequentially layered on the second electrode 940 and on aportion of the compensation layer 930 not covered by the secondelectrode 940. The first electrode 960 is patterned on the secondconductive layer. The first electrode 960 shown in FIG. 9 is formed ononly a portion of the piezoelectric layer 950, but may have otherconfigurations. The compensation layer 970 is layered on the firstelectrode 960 and on a portion of the piezoelectric layer 950 notcovered by the first electrode 960. The air cavity 920 below the bulkacoustic resonance unit is formed by removing the sacrificial layerpatterned on substrate 910. Various techniques for removing thesacrificial layer are well known to one of ordinary skill in the art,and therefore will not be described in detail herein. After the aircavity 920 has been formed, the air cavity may be filled with air or adielectric material as described above.

The compensation layer 930 and the compensation layer 970 may include asilicon oxide-based material or a silicon nitride-based material.

The compensation layer 930 and the compensation layer 970 may be formedby depositing an impurity element using an impurity gas including theimpurity element based on an in-situ deposition simultaneously withdeposition of SiO₂ or Si₃N₄. Alternatively, the compensation layer 930and the compensation layer 970 may be formed by doping SiO₂ or Si₃N₄with the impurity element by ion implantation after the SiO₂ or Si₃N₄are deposited.

FIGS. 10 through 18 are sectional views illustrating other examples of alayered structure of a BAWR.

Referring to FIG. 10, an air cavity 1020 is disposed on a portion of asubstrate 1010, and a compensation layer 1030 is disposed on the aircavity 1020 and on a portion of the substrate 1010 not covered by theair cavity 1020. A lower portion electrode 1040 is disposed on a portionof the compensation layer 1030, and a piezoelectric layer 1050 isdisposed on the lower portion electrode 1040 and on a portion of thecompensation layer 1030 not covered by the lower portion electrode 1040.A compensation layer 1060 is disposed on the piezoelectric layer 1050,and an upper portion electrode 1070 is disposed on a portion of thecompensation layer 1060. When compared to the BAWR of FIG. 9, the BAWRof FIG. 10 is different in that the compensation layer 1060 is below theupper portion electrode 1070.

Referring to FIG. 11, an air cavity 1120 is disposed on a portion of asubstrate 1110, and a compensation layer 1130 is disposed on the aircavity 1120 and on a portion of the substrate 1110 not covered by theair cavity 1120. A lower portion electrode 1140 is disposed on a portionof the compensation layer 1130, and a piezoelectric layer 1150 isdisposed on the lower portion electrode 1140 and on a portion of thecompensation layer 1130 not covered by the lower portion electrode 1140.A compensation layer 1160 is disposed on the piezoelectric layer 1150,and an upper portion electrode 1170 is disposed on a portion of thecompensation layer 1160. A compensation layer 1180 is disposed on theupper portion electrode 1170 and on a portion of the compensation layer1160 not covered by the upper portion electrode 1170. When compared tothe BAWR of FIG. 9, the BAWR of FIG. 11 is different in that thecompensation layer 1160 is additionally included below the upper portionelectrode 1170.

Referring to FIG. 12, an air cavity 1220 is disposed on a portion of asubstrate 1210, and a compensation layer 1230 is disposed on the aircavity 1220 and on a portion of the substrate 1210 not covered by theair cavity 1220. A lower portion electrode 1240 is disposed on a portionof the compensation layer 1230, and a piezoelectric layer 1250 isdisposed on the lower portion electrode 1240 and on a portion of thecompensation layer 1230 not covered by the lower portion electrode 1240.An upper portion electrode 1260 is disposed on a portion of thepiezoelectric layer 1250. When compared to the BAWR of FIG. 9, the BAWRof FIG. 12 is different in that the single compensation layer 1230 isused.

Referring to FIG. 13, an air cavity 1320 is disposed on a portion of asubstrate 1310, and a lower portion electrode 1330 is disposed on theair cavity 1320 and on a portion of the substrate 1310 not covered bythe air cavity 1320. A piezoelectric layer 1340 is disposed on the lowerportion electrode 1330 and on a portion of the substrate 1310 notcovered by the lower portion electrode 1330, and an upper portionelectrode 1350 is disposed on a portion of the piezoelectric layer 1340.A compensation layer 1360 is disposed on the upper portion electrode1350 and on a portion of the piezoelectric layer 1340 not covered by theupper portion electrode 1350. When compared to the BAWR of FIG. 9, theBAWR of FIG. 13 is different in that the single compensation layer 1360is used.

Referring to FIG. 14, an air cavity 1420 is disposed on a portion of asubstrate 1410, and a compensation layer 1430 is disposed on the aircavity 1420 and on a portion of the substrate 1410 not covered by theair cavity 1420. A lower portion electrode 1440 is disposed on a portionof the compensation layer 1430. A compensation layer 1450 is disposed onthe lower portion electrode 1440 and on a portion of the compensationlayer 1430 not covered by the lower portion electrode 1440. Apiezoelectric layer 1460 is disposed on the compensation layer 1450. Acompensation layer 1470 is disposed on the piezoelectric layer 1460. Anupper portion electrode 1480 is disposed on a portion of thecompensation layer 1470. A compensation layer 1490 is disposed on theupper portion electrode 1480 and on a portion of the compensation layer1470 not covered by the upper portion electrode 1480. When compared tothe BAWR of FIG. 9, the BAWR of FIG. 14 is different in that thecompensation layer 1450 is additionally disposed on the lower portionelectrode 1440, and the compensation layer 1470 is additionally disposedbelow the upper portion electrode 1480.

Referring to FIG. 15, an air cavity 1520 is disposed on a portion of asubstrate 1510, and a compensation layer 1530 is disposed on the aircavity 1520 and on a portion of the substrate 1510 not covered by theair cavity 1520. A compensation layer 1540 is disposed on thecompensation layer 1530, and a lower portion electrode 1550 is disposedon a portion of the compensation layer 1540. A piezoelectric layer 1560is disposed on the lower portion electrode 1550 and on a portion of thecompensation layer 1540 not covered by the lower portion electrode 1550.An upper portion electrode 1570 is disposed on a portion of thepiezoelectric layer 1560, and a compensation layer 1580 is disposed onthe upper portion electrode 1570 and on a portion of the piezoelectriclayer 1560 not covered by the upper portion electrode 1570. Thecompensation layer 1590 is disposed on the compensation layer 1580. Whencompared to the BAWR of FIG. 9, the BAWR of FIG. 15 is different in thatthe compensation layer 1540 is additionally disposed below the lowerportion electrode 1550, and the compensation layer 1590 is additionallydisposed. When thicknesses of compensation layers included in a BAWR areequal, in a case where two or more layered compensation layers areseparately disposed on or below an upper portion electrode or disposedon or below a lower portion electrode as shown in FIG. 15, a Q factor ofthe BAWR is improved.

Referring to FIG. 16, an air cavity 1620 is disposed on a portion of asubstrate 1610, and a compensation layer 1630 is disposed on the aircavity 1620 and on a portion of the substrate 1610 not covered by theair cavity 1620. A compensation layer 1640 is disposed on thecompensation layer 1630, and a lower portion electrode 1650 is disposedon a portion of the compensation layer 1640. A piezoelectric layer 1660is disposed on the lower portion electrode 1650 and on a portion of thecompensation layer 1640 not covered by the lower portion electrode 1650.An upper portion electrode 1670 is disposed on a portion of thepiezoelectric layer 1660, and a compensation layer 1680 is disposed onthe upper portion electrode 1670 and on a portion of the piezoelectriclayer 1660 not covered by the upper portion electrode 1670. Whencompared to the BAWR of FIG. 9, the BAWR of FIG. 16 is different in thatthe compensation layers 1630 and 1640 are both included, as opposed tothe single compensation layer 930.

Referring to FIG. 17, an air cavity 1720 is disposed on a portion of asubstrate 1710, and a compensation layer 1730 is disposed on the aircavity 1720 and on a portion of the substrate 1710 not covered by theair cavity 1720. A lower portion electrode 1740 is disposed on a portionof the compensation layer 1730. A piezoelectric layer 1750 is disposedon the lower portion electrode 1740 and on a portion of the compensationlayer 1730 not covered by the lower portion electrode 1740. An upperportion electrode 1760 is disposed on a portion of the piezoelectriclayer 1750, and a compensation layer 1770 is disposed on the upperportion electrode 1760 and on a portion of the piezoelectric layer 1750not covered by the upper portion electrode 1760. A compensation layer1780 is disposed on the compensation layer 1770. When compared to theBAWR of FIG. 9, the BAWR of FIG. 17 is different in that thecompensation layers 1770 and 1780 are both disposed, as opposed to thesingle compensation layer 970. That is, another compensation layer isfurther added.

Referring to FIG. 18, a BAWR includes a substrate 1810, an air cavity1820, a bulk acoustic wave resonance unit, a compensation layer 1830,and a compensation layer 1870. The air cavity 1820 is disposed on aportion of the substrate 1810. The air cavity 1820 changes an impedanceof the BAWR to improve an acoustic wave reflection characteristic.

The bulk acoustic wave resonance unit includes a lower portion electrode1840, a piezoelectric layer 1850, and an upper portion electrode 1860.The upper portion electrode 1860 is layered so that at least one area ofthe upper portion electrode 1860 has a different thickness than aremaining area of the upper portion electrode 1860. A difference inthickness causes a difference in impedance between areas havingdifferent thicknesses. Due to the difference in impedance, an acousticwave reflection characteristic is improved, and an electriccharacteristic of the BAWR is improved. The at least one area having thedifferent thickness may be formed by removing or etching a layeredsacrificial layer.

FIG. 19 is a block diagram of an example of a duplexer.

Referring to FIG. 19, a duplexer 1900 includes a first filter 1910, asecond filter 1920, and a phase shifter 1930. The first filter 1910 isconfigured to filter a transmission signal received from a transmitinput of the duplexer 1900, and output the filtered transmission signalto an antenna 1940. The phase shifter 1930 is configured to shift aphase of a received signal received from the antenna 1940 to preventsignal interference between the first filter 1910 and the second filter1920, and output the phase-shifted received signal to the second filter1920. The second filter 1920 is configured to filter the phase-shiftedreceived signal received from the phase shifter 1930, and output thefiltered phase-shifted received signal to a receive output of theduplexer 1900.

The first filter 1910 and the second filter 1920 operate at differentpredetermined resonance frequencies. The resonance frequencies of thefirst filter 1910 and the second filter 1920 may be adjusted to bedifferent from each other by adjusting thicknesses of correspondingpiezoelectric layers to be different from each other. Each of the firstfilter 1910 and the second filter 1920 includes a bulk acoustic waveresonance unit and at least one compensation layer. The bulk acousticwave resonance unit includes a lower portion electrode, a piezoelectriclayer, and an upper portion electrode, each of which include a materialthat modifies a resonance frequency based on a change in a temperature.The at least one compensation layer includes a material that adjusts theresonance frequency modified based on the change in the temperature in adirection opposite to a direction of the modification to adjust a TCF ofthe bulk acoustic wave resonance unit.

Several examples have been described above. Nevertheless, it should beunderstood that various modifications may be made in these examples. Forexample, suitable results may be achieved if the described techniquesare performed in a different order and/or if components in a describedsystem, architecture, device, or circuit are combined in a differentmanner and/or replaced or supplemented by other components or theirequivalents. Accordingly, other implementations are within the scope ofthe claims and their equivalents.

What is claimed is:
 1. A film bulk acoustic wave resonator (BAWR)comprising: a substrate; a bulk acoustic resonance unit comprising afirst electrode, a second electrode, and a piezoelectric layer disposedbetween the first electrode and the second electrode; a firstcompensation layer disposed above the bulk acoustic resonance unit; anda property compensation layer disposed above the first compensationlayer, wherein the property compensation layer is disposed above theedges of a surface of the compensation layer so that a remaining portionof the surface between the edges is not covered by the propertycompensation layer.
 2. The BAWR of claim 1, wherein the firstcompensation layer adjusts a temperature coefficient of the bulkacoustic wave resonance unit.
 3. The BAWR of claim 1, wherein the firstcompensation layer comprises a silicon oxide-based material, a siliconnitride-based material, silicon oxide doped with an impurity, or siliconnitride doped with the impurity.
 4. The BAWR of claim 3, wherein theimpurity comprises at least one element selected from the groupconsisting of arsenic (As), antimony (Sb), phosphorus (P), boron (B),germanium (Ge), silicon (Si), and aluminum (Al.).
 5. The BAWR of claim1, further comprising: a second compensation layer disposed below thesecond electrode
 6. A duplexer comprising: a phase shifter configured toshift a phase of a received signal, and output the phase-shiftedreceived signal; and a filter configured to filter the phase-shiftedreceived signal output from the phase shifter, and output the filteredphase-shifted received signal to a receive output of the duplexer;wherein the filter comprises a film bulk acoustic source resonatorcomprising: a first electrode, a second electrode, a piezoelectric layerdisposed between the first electrode and the second electrode, acompensation layer disposed above the bulk acoustic resonance unit, anda property compensation layer disposed above the compensation layer,wherein the property compensation layer is disposed above the edges of asurface of the compensation layer so that a remaining portion of thesurface between the edges is not covered by the property compensationlayer.